Electron discharge device



Aug. 12, 1958 Filed Nov. 25, 1955 R. M N. BOWIE ELECTRON DISCHARGEDEVICE 3 Sheets-Sheet 1 I 24 A 22 MAGNETIC v K V /,r F

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INVENTOR ROBE RT M. BOWIE ATTORNEY 12,1958 R. MCN. BOWlE 2,847,597

ELECTRON DISCHARGE DEVICE Filed Nov. 25, 1955 5 Sheets-Sheet 2 Fl G.3 W36 so as I INVENTOR ROBERT M.BOW|E BY W ATTO R N EY 1953 R. MON. BOWIE2,847,597

ELECTRON DISCHARGE DEVICE Filed Nov. 25, 1955 3 Sheets-Sheet 3 33 I asFIG.6

INV TOR ROBE M.BOWIE BY My ATTORNEY Unite ELECTRON DISCHARGE DEVICERobert McNeil Bowie, Manhasset, N. Y., assignor to Sylvania ElectricProducts Inc, a corporation of Massachusetts Application November 25,1955, Serial No. 548,943

11 Claims. (Cl. 313--70) electron beams in a common envelope and findapplication in many diverse electronic fields. For example,Oscilloscopes adapted to produce a plurality of test pattern displayssimultaneously make use of such tubes, utilizing one electron beam foreach display. Further, such tubes find increasing application in thecolor television art. For example, a tube utilizing two electron beamsand adapted for color image display is disclosed in a copendingapplication of Benjamin F. Tyson, Serial No. 516,668, filed June 20,1955, and a tube of this general type utilizing four electron beams in acommon envelope is disclosed in a copending application of Robert M.Bowie, aerial No. 477,161, filed August 24, 1953, now Patent No.2,827,591, both of the above cases being assigned to the assignee ofthis application.

Certain multi-beam cathode ray tubes incorporate a separate electron gunstructure for each beam. The incorporation of two or more electron gunsin a single cathode ray tube of this type represents at best a complexand costly manufacturing procedure; each electron gun is a separatestructure and must be separately mounted in the gun in such manner thatall guns are fixedly spaced from each other. Extremely close tolerancesare often required. Moreover, the difiiculties of preventingelectricalinteraction between two or more guns require special shieldingarrangements and the like.

I have succeeded in overcoming these difliculties and thereby greatlysimplifying the construction of multibeam cathode ray tubes by utilizinga single electron beam source and a beam splitting member separated frombut in intimate association with the source in such manher that anydesired number of electron beams can be derived from the single beamsource.

Accordingly, it is an object of the present invention to improvemulti-beam cathode ray tubes through the use of a single electron beamsource and beam splitting means separated from and yet in intimateassociation with said source for deriving a plurality of-electron beamstherefrom.

Another object is to improve electron gun structures through the use ofa single electron beam source and. means separated from but in intimateassociation with said source to derive at least two beams therefrom andat the same time controlling the intensity of at least one of saidbeams.

Still another object is to provide a new and improved cathode ray tubein which a plurality of intensity controlled electron beams are derivedfrom a single electron beam source by means of a beam splitting slottedmember and intensity control electrodes spanning a portion of theslotted member.

These and other objects of my invention will either be explained or willbecome apparent hereinafter.

a stout O In my invention, an electron source such as a cathode isinserted in the neck of a cathode ray tube envelope. The source producesan electron stream which flows to ward the tube screen. interposedbetween the source and the screen of the cathode ray tube is a structurewhich derives a plurality of electron beams from said source. Thisstructure is provided with at least one slot through which the electronstream flows and further includes beam splitting means associated withthis slot. Said beam splitting means divide the slot into a plurality ofsections and cause the stream to be distributed or apportioned. withineach section thereby producing a like plurality of electron substreams,each substream forming a single electron beam.

When the slot is rectangular in shape, all the electron beams soproduced are substantially coplanar at the points of origin and at thepoints of termination at the screen. When the shape of the slot isvaried from rectangular, non-coplanar beams can be produced. The beamsin the region intermediate the points of origin and the points of screentermination may and generally do intermingle to follow substantially thesame path through the focusing and deflecting means commonly employed incathode ray tubes.

I further provide intensity control means associated with said slot tosepaartely control the intensity of at least one of said plurality ofbeams, as for example an intensity control electrode spanning the slot.

Illustrative embodiment of my invention will now be described in moredetail with reference to the accompanying drawings wherein Pig. 1 is alongitudinal section of a multi-beam cathode ray tube in accordance withmy invention;

Fig. 2 is an exploded view of the electron gun structure used in Fig. 1;

Fig. 3 is an enlarged isometric exploded view of the cathode, slottedelectrode and supporting structure used in Fig. 2;

Fig. 4 is a cross-sectional view of the slotted member and intensitycontrol elements as used in Fig. 2;

Fig. 5 is an enlarged isometric view of an alternative structure toreplace that shown in Fig. 3; and

Fig. 6 is a longitudinal sectional view of the structure shown in Fig.5.

Referring now to Fig. 1 there is shown a multi-beam, in this example, adual beam cathode ray tube 10 which can be either of the monochrome orcolor type. The tube includes a single electron gun structure identifiedgenerally at 12 which produces two electron beams 14 and 16. Theintensities of these beams are controlled by separate grids. The beamsare vertically displaced from each other and are focussed, for example,by electrostatic focusing lens associated with electrode 22 anddeflected, for example, through the action of magnetic yoke 24 to strikethe image screen 26 in the manner indicated.

The gun structures as shown in Figs. 2, 3, and 4 include a ceramicrectangular block 30. The block is provided with a rectangular channel32 in which is mounted a conventional cathode 34 having an electronemissive plane or cylindrical surface which faces the tube screen. Thecathode is of the indirectly heated type. The heater filaments andconnections are conventional and are not shown here.

The block is also provided with grooves which con tain cathode supportand spacing members. 36. 'These members are bonded to the block and holdthe cathode in place by supporting each end thereof. Sections. 38 (Fig.3) of said spacing members project downward into the channel thuspositioning the electron emissive surface of the cathode somewhat belowthe top surfaces 40 of the ceramic block.

Additional grooves in the block contain a beam split- 3 ting member 42and two beam intensity control elements 44 and 4-6.

Wire member 42 is flush with the top block surface 40. The intensitycontrol elements 4 5, 46 are positioned below these surfaces.

The emissive surface of the cathode is displaced below the surface 40oi'member 42 and elements 44 and 46 so as to provide a finite spacingther'ebetween.

Secured to the top block surfaces is 'a'slotted metal electrode 50provided with a rectangular slot 52 having its long dimension extendingparallel to the axis of the cathode. The slot is so positioned withrespect to "the member 42 and control elements 44 and 46 that member 42spans the width of the slot and divides the slot into two verticallydisplaced sections 54 and 56. These sections may or may not be equaldepending upon thebeam cross-section requirements. Each of the controlelements also spans the width of the slot, one wire being positioned ineach slot section.

Theslotted electrode and member 4-2 are maintained in electrical contactwith each other and form an equipotential surface; the control elementsare insulatedly separated from the slotted electrode and member 42. Atab connection 58 is connected to the slotted member in conventionalmanner.

When the entire tube is assembled and rendered operative, the electronstream generated by the cathode passes through the slot. The electronspassing through the slot will tend to pass around member 42, thusforming two electron sub-streams or beams passing through slot sections54 and '56, respectively.

When voltages are supplied to the control elements, each beam isintensity modulated in conventional manner; these beams are isolatedfrom each other.

By ornitting'one or both control elements, each or both beams can begenerated substantially free of intensity modulation. By increasing thenumber of 'beam splitting members, theslot can be divided into a largernumber of subsections and the number of beams can be correspondinglyincreased. Additional control elements can be used I to control theintensity of these additional beams. Further, it will be apparent thatthe shape of the ceramic block and cathode can be varied as necessary.For example, a cylindrical ceramic block having a central recess and adisc-like cathode mounted within the recess can be used. Moreover, thespacing between beams can be variedby varying the thickness of the beamsplitting members.

The above structures can be adapted for automatic as sembly in themanner shown in Figs. 5 and 6. The edges of the ceramic are threadedwith a bifilar or double thread with very fine pitch. Grooves areprovided for the cathode supports in the manner previously indicated andthe cathode is placed Within the block channel.

The center of the block is then wound with the two control elements andwith three'beam splitting members. (In this example, two additionalbeamsplitting members are used.) These members are positioned about theedges of the slot to prevent fringe electric fields established aboutthese edges from interacting with the electron beams. The beam splittingmembers have a relatively large cross-section and are to be inelectrical contact with the slotted electrode. The control elements havea relatively small cross-section and are physically displaced from thebeam splitting members and the slotted electrode.

A suitable frit is painted on the top surfaces of the block and on theelements and beam splitting members. The frit is then carefully removedfrom the top ofthe members. The slotted electrode, gold plated on itsunderside, is placed in contact with the beam splitting members.

The entire assembly is then fired in a non-oxidizing atmosphere tosolder the beam splitting members to the slotted electrode and to fritdown the wires. The members and the control elements can then be severedat the bottom of the block and suitably trimmed at the upper edge. Thecontrol elements are trimmed only at one end to provide suitable gridconnections.

The diameter of the beam splitting members determines the spacingbetween the ceramic block and the slotted electrode. The controlelements being of smaller diameter than the slotted electrode do notcome in contact therewith. Hence, by varying the relativecross-sectional dimensions, the slotted electrode-ceramic block spacingcan be varied as necessary.

While I have shown and pointed out my invention as applied above, itwill be apparent to those skilled in the art that many modifications canbe made within the scope and sphere of my invention as defined in theclaims which follow.

What is claimed is:

1. In combination with first means for generating a single electronstream and second means for collecting said stream, a first electricallyconductive member provided with a slot and positioned between said firstand second means in such manner that said slot is interposed in the pathof said stream in intimate association with said first means; at leastone second electrically conductive member electrically connected to saidfirst member and spanning said slot so as to divide said slot into twosections, said stream being apportioned between said sections to formcorresponding electron beams as it passes through said slot; and a firstbeam intensity control electrodespanning one of said slot sections tocontrol the intensity of the corresponding beam, said electrode beingelectrically insulated from said first and second members.

-2. In combination with first means for generating a single electronstream and second means for collecting said stream, a first electricallyconductive member provided with a slot and positioned between said firstand second means in such manner that said slot is interposed in the pathof said stream in intimate association with said first means; at leastone second electrically conductive member electrically connected to saidfirst member and spanning said slot so as to divide said slot into twosections, said stream being apportioned between said sec-- tions to formcorresponding electron beams as it passes through said slot; and firstand second beam intensity ,control electrodes electrically insulatedfrom each other and from said first and second members, each of saidelectrodes spanning a corresponding slot section to control theintensity of said corresponding beam.

3. In combination with first means for generating a single electronstream and second means for collecting said stream, a first electricallyconductive member provided with a slot and positioned between said firstand second means in such manner that said slot is interposed in the pathof said stream in intimate association with said first means; at leastone second electrically conductive member electrically connected to saidfirst member and spanning said slot so as to divide said slot into twosections, said stream being apportioned between said sections to formcorresponding electron beams as it passes through said slot; and twoadditional beam configuration controlling second members spanning saidslot in positions remote from the said one second member, all of saidsecond members being parallel and being electrically interconnectedthrough said slotted member to each other.

4. In combination, an electrically non-conductive member provided with arecess; a cathode structure positioned within said recess and secured tosaid member; an electrical conductive electrode secured to said memberadjacent said recess, said electrode having a slot communicating with atleast a portion of said structure; and at least one electricallyconductive element electrically connected to said plate and spanningsaid slot.

5. The combination as set forth in claim 4 further including at leastone additional element insulated from said conductive element and saidelectrode and spanning said slot at a point spaced apart from saidconductive element.

6. The combination as set forth in claim 5 wherein said element isinterposed between said member and said electrode.

7. In combination, an electrically non-conductive 8. The combination asset forth in claim 7 furtherincluding at least one control elementspanning said slot in a position spaced apart from said member.

9. The combination asset forth in claim 8 wherein said element and saidmember are interposed between said block and said plate.

10. The combination as set forth in claim 9 further including twoadditional like members, said additional 6 members spanning said slot onopposite sides of said one member, said control element being positionedintermediate two of said members.

11. The combination as set forth in claim 10 wherein the cross sectionof said member exceeds that of said element whereby the spacing betweensaid block and said plate is determined by the cross section of saidmembers and said control element is electrically isolated from saidmember.

References Cited in the file of this patent UNITED STATES PATENTS2,141,415 Schlesinger Dec. 27, 1938 2,165,028 Blumlein Iuly 4, 19392,256,297 Smith et al -2 Sept. 16, 1941 2,457,495 Rochester Dec. 28,1948 2,506,627 Barford May 9, 1950 2,512,858 Hegbar June 27, 19502,587,074 Sziklai Feb. 26, 1952 2,732,516 Speedy Jan. 24, 1956 2,758,234Hensel Aug. 7, 1956

